Glass-like substances occur naturally and have been used by humans for generations. The best-known is odsidian, produced by the intense heat of volcanoes. Origins of the first manufactured glass are lost in antiquity. It is thought that seagoing Mediterranean merchants accidentally combined a form of soda, sand and limestone with their beach campfires and noticed the hard, clear substance left in the ashes. These basic ingredients are used in glassmaking to this day.

Through conquest, the art was taken to Egypt where the oldest relics are dated at 2000 B.C. Egyptians established the first known glass factory around 1400 BC. It is also believed that Alexander the Great was buried in a glass coffin. From Egypt the technique was taken to Rome. By 500AD, the Roman empire had helped to spread glass-making techniques throughout the Mediterranean and beyond, to northern Europe and Britain where it continued to develop. Between the 7th and 13th centuries, the 'crown' method of spinning a gob of molten glass on a hollow rod or punty was used. This resulted in a bubble of glass being flattened into a disc approxiametely one metre in diameter, from which small pieces were cut from the outside, leaving the worst quality in the centre. The bulls-eye or bullion ironically is now the most sought after piece. Alternative processes devised, included the ‘crown’ process, which entailed adding a disc to the end of the rod and blowing a glob of molten glass onto the disc. It was then turned with speed by means of the rod, centrifugal force spinning a large flat disc.

Flat glass was for centuries produced by blowing a large bubble of molten glass at the end of a metal tube. After cutting off the ends and splitting the resultant cylinder in half, the two pieces were softened by reheating and beaten flat on a large stone using a broad wooden paddle. The blown, cylinder process continued to be developed until, in the mid 19th century, cylinders up to 12 metres long were being successfully split. The Crown method was subsequently replaced by the cylinder blown and later the cyliber drawn process in 1903. In principle a long balloon of glass was blown or drawn, split and flattened and then allowed to cool slowly to avoid stress in the glass, however sizes were again limited.

It was in 1913 that continuous processes such as; the Fourcault process (Belgium); the Colburn - Libbey - Owens process (USA); and the most successful of all, the PPG Pittsburgh process (USA). All involved drawing the glass up vertically out of a tank of molten glass, the edges being held by knurled rollers to retain the ribbon width.

The sheet glass produced by these methods gave a good strong fire finish, but the very action of pulling upwards meant the product contained inherent bands of distortion which resulted in poor optical quality and terrible reflections.

Where true optical quality was required in mirrors or large shopfront windows, a polished plate glass was needed. The polished plate process involved cast or sheet glass being ground and polished to achieve the desired quality.By 1938 the process had been developed to a stage where a continuous ribbon of cast glass was ground and polished on both surfaces simultaneously, first with sand then iron oxide. Apart from being extremely messy, the processing line was longer than the ocean liner The Queen Mary (xxxft), and was correspondingly, very costly. The polished plate glass technique is still used today in the manufacture of Polished Wired glass and Lead glass.

The quantum leap came in the late 1950's when Pilkington launched their Float Glass process, which has since been licensed to glass makers throughout the world. This innovative process, invented by Sir Alastair Pilkington, involves molten glass being 'floated' on a bath of molten tin, while being heated on the top surface. The resulting product is a hard fired optically true finish that requires no further processing to the actual product other than cutting for distribution. The Float Glass process is still the current manufacturing method for 90% of the world's flat glass production.

While manufacturing methods have changed dramatically over the last century, the basic ingredients used in glass making are still very much the same.